High power transmit-receive box



Aug. 4, 1953 L D. sMuLLlN 2,647,952 HIGH Pom 'mmm-RECEIVE Box Filed Aug. 2, 1945 'f INVENTOR 32 LOUIS D, SMULLIN ATTORNEY Patented Aug. 4, 1953 UNITED STATES-I OFFICE'l 2,647,952w1f I v i HIGH POWER TRANsMiriEjCEIvE'Boxf. Louis D. smuuin,l .ArlingtongffMassg assrgorffby v mesne assignments, -to the'llnited :Statesof America as represented by the Secretary of-,the

Navy

Application August 2, 1945,"Serla`lNo608f593 if 2 Claims. H(Cl. S33- 13) This invention relates to transmit-receive boxes and more particularly to an improved box of the class indicated having novel tuning means inserted thereinA and constructed to provide a minimumof leakage power through the box.

Transmit-receive boxes, hereinafter referred to as ITR boxes, are commonly used in connecl tion vwith transmit-receiveV circuits having a common antenna to electrically cut off the receiver from the circuit at all times during' which the-transmitter is in operation. TR boxes of common construction have not proven entirely satisfactory due to leakage of power through the boxduring intervals in which the'transmitter is operative, thereby sho-rtem'ngthe life of the crystal ydetector commonly `used in the receiver circuit.

An object of this invention is'to provide an im- I proved transmit-receive -box of such construction as to afford -a minimumfof power leakage'l through the box'riA Another object'of this? invention is to provide a TR box having adjustable means for increasing thfdireet coupling attenuation' through lthe Y resonant cavity of the box.

A particular object of thisA invention is to provide a tunable TR box havingmeans for `a`d' just'ablytuning'the resonant cavity of the box..A

A more particular object of this invention is to provideY a 'TR/'box having attenuationplug'sv electrically connected to two opposite walls of the resonant cavity irrespective of the depthy to which the plugs may be inserted in said'cavity Further objects and advantages of this invention -as well as its construction, arrangementf-l` and operation, will be apparent from the following description and claims in conjunction with the accompanying drawings, in which:

Fig. '1 is a schematic diagram of a section of a wave guide having a standard TR box connected directly to one side of the guide.

Fig. 2 is a schematic diagram of one form of the present invention including tuning plugs of a construction and operation hereinafter to be described.

Fig. 3 is a front elevation taken along the lines III- III of Fig. 2.

Fig. 4 is a schematic diagram of a second embodiment of the invention shown in Fig. 2 having a plurality of uniformly disposed tuning plugs adjustably mounted on the wall of the TR box.

Referring to Fig. 1, there is shown a schematic diagram of a section of a Wave guide with a standard TR box having a wal1 2| enclosing a resonantfc'avity-ZZ connected vdirectlyto one side of wave guide20 by means of an opening or wing-H- 'I'he out-yx putv'couplingof'the TRv box is by Ameans of a s probe'or lloop 24,- coupling the magnetic -lflelc'LQl Magnetic eld distribution'4 lines A-25 are A'sho-wn Y for; thecondition in which the 'TR box'is -red. pointing out diagrammatically the manner -in which `thefdistribution of the magnetic -eldfalls oir-exponentially from window `23 to output probe-tf 24u-One of ahv pair of cones'commonlyausedin TRtubes is shown and indicatedby numeral 26.

Fig. 2 illustratespne -form of the'vpresent-i-n-f r vention in which allparts are common to those-1Y of Fig. 1, but'lincludingmetallicplugs `27| and,- 28l of electrically vconductive material -lfor short-1 ing out themagnetie` eldas it progresses across.,I

dowf23 in thesidef'of the waveguide.

the box.

are indicated at -29 and 26 respectively. A

Fig. 3 is a front elevation-takenalong .thelines III--IIIr of Fig. 2 further Lillustrating the inven-i u tion las shownfin Fig. -2. A pair-y of wallsilll andA 3| are shown which, together withw-all 2-|,-Ycomv-' plete the enclosureof resonant -cavity- 22.#'1R

height of wall 2|. The inner 'surfaces of Walls 30 and-'3| 'areprovided'with `thre'aded'.portions so that plugs' 21 and `28 mayibe moved 'intoand'ifr out of cavity 22, while retaining electrical contact with walls 30 and 3| at all times. In this manner, plugs 21 and 28 provide a complete block to the passage of electromagnetic radiation for the depth of their insertion in cavity 22. In addition to completely physically blocking oft' cavity 22 in so far as they are inserted into the cavity, plugs 21 and 28, at the same time, electrically short out the magnetic waves to walls 3|) and 3|. It has further been discovered that if D be the diameter of a TR. box as shown in Fig. 1 tuned for resonance at a certain frequency, and if d be the distance between opposite faces of attenuation plugs as shown in Fig. 2 in which the plugs are adjusted to cause the box to `become resonant at the same frequency, the value of d is much smaller than the value of D of a standard TR box not supplied with attenuation plugs as contemplated by our invention. It will As shown, plugs 28 and I28 are adjust-f ably' `mounted through Vsuitable openings in wall 2| so that-they may be movedfintofand out of resonant -cavity 22.- A glass-TR. tube and one-fof the cones-forming the spark gap of saidtube-vr` off exponentially with the distance therebetween, the leakage of power by direct coupling may be reduced to a minimum without loss of resonant tuning of the box. It is the combination of increased distance across the box and snorting-out effect of the attenuation plugs that assures a minimum of power leakage from input source to output probe.

Fig. 4 is similar in all respects to Fig. 3 with the exception of the addition of a second pair of attenuation plugs and theA orientation of the plugs with respect to the input window and output probe of the tube. As shown, four adjustable attenuation plugs 32, 33, 34 and 35 are employed to short out the magnetic eld and to provide resonant tuning of the box. In this embodiment of the invention, the effective diameter of the TR box is the distance between the inside faces of the opposite plugs. It Will readily be understood from the foregoing discussion in connection with Figs. 2 and 3 that the coupling space between window 23 and output probe 24 may be substantially increased over that of a standard TR box, while oppositely disposed attenuation plugs 32, 33, 34, and 35, respectively, makel it possible for the resonance of the box to be tuned in spite of this increase in coupling space. ily be understood that since the diameter of these attenuation plugs is equal to the thickness of the TR box, and since these plugs are electrically connected to the walls of the box at all times, the combination blocking and snorting out effect of the plugs together with the increased coupling space made possible through use of the plugs provides an improved TR box' inwhich the power leakage from input source to output probe may be reduced to a minimum.

While two embodiments of the invention have been disclosed and described, it is to be understood that various modifications and changes may be made in this invention without departing from the spirit and scope thereof as set forth in the appended claims.

What is claimed is:

lfrAftunable transmit-receive box comprising twofiparallel plane electrically conductive Walls Likewise, it will readjoined to a cylindrical electrically conductive Wall, said walls encosing a resonant cavity, means at said cyindrical wall for introducing electromagnetic energy into said cavity, additional means at said cylindrical wall diametrically opposite said introducing means for extracting said electromagnetic energy, and a pair of electrically conductive plugs adjustably mounted in said cylindrical wail and extending into said cavity, one

member of said pair being disposed diametrically opposite the other member or said pair, a line extending diametrically through said pair of plugs being transverse to a line extending diametrically through said introducing and extracting means, each of said plugs being equal in diameter to the spacing between said parallel walls and being in electrical contact with said parallel walls irrespective of the depth to which it is inserted into said cavity.

2. A tunable transmit-receive box comprising two parallel plane, electrically conductive walls joined to a cylindrical electrically conductive wall, said Walls enclosing a resonant cavity, means for introducing electromagnetic energy through said cylindrical wall into said cavity, means for extracting said energy from said cavity through said cylindrical wall, said introducing means and said extracting means being diametrically opposite one another, and a plurality of pairs of electrically conductive plugs adjustably mounted in said cylindrical wall and extending into said cavity, each member of each pair of said plugs being disposed diametrically opposite the other member of the same pair, said plugs being disposed symmetrically with respect to a line extending through said introducing means and said extracting means, each of said plugs also being equal in diameter to the spacing between said parallel walls and being in electrical contact with said parallel walls irrespective of the depth to which it is inserted into said cavity.

LOUIS D. SMULLIN.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,106,769 Southworth Feb. 1, 1938 2,306,682 Samuel Dec. 22, 1942 2,402,663 Ohl June 25, 1946 2,406,402 Ring Aug. 2'7, 1946 2,410,109 Schelleng Oct. 29, 1946 2,415,242 Hershberger Feb. 4, 1947 2,442,671 Tompkins June l, 1948 2,445,445 Marcum July 20, 1948 2,466,136 Tuller Apr. 5, 1949 

